SATURN SC2 HEATER PROBLEM

1996 Saturn SC2 • 15,000 miles

THE HEATER BLOWS HOT AIR OUT THE VENTS IN THE CAR FOR ABOUT FIVE SECONDS AND AFTER THAT IT GETS COLD NOT SURE WHAT THE PROBLEM IS IVE REPLACED THERMOSTAT AND MADE SURE EVERYTHING IS FLOWING RIGHT AND THE TEMPERATURE IS GOOD I THINK ITS ETHER A VACUUM HOSE THAT CONTROLS A DAMPER OR SOMETHING ELSE INSIDE UNDER THE DASH BUT I DON'T REALLY WANT TO START TAKING A BUNCH OF STUFF APART TO FIGURE OUT THE PROBLEM I JUST WANT TO KNOW WHAT IT IS BEFORE HAND AND FIX IT PLEASE LET ME KNOW WHAT YOU THINK ITS IS ANY IDEAS THANKS